Lighting systems for road vehicles

ABSTRACT

1. A lighting system for a road vehicle, comprising in combination a light source and associated lens for producing a beam of light illuminating the road in front of the vehicle, a mask having therein an aperture, focusing means associated with the light source and arranged so that an image of the light source appears in the aperture, and a well defined image of the aperture is projected forwardly to constitute said beam, a shutter movable from a rest position across the aperture, and means sensitive to light received from an oncoming vehicle for progressively moving the shutter across the aperture so as to cut off sufficient of the beam to avoid dazzling the driver of the oncoming vehicle.

D United States Patent [151 3,673,42 1

Hicks et a]. 1 *June 27, 1972 [54] LIGHTING SYSTEMS FOR ROAD [56]References Cited VEHICLES UNITED STATES PATENTS [72] Inventors: HarrisVernon Hicks, Lichfield Staffs;

Kenneth J Jones, Sutton coldfield, 2,753,487 7/1956 Bone ..315/821,796,239 3/1931 Byles ..250/229 X both of England 2,066,680 l/1937G1eskieng.. ..315/82 X A gn e J p Lucas (Industries) Limited, Bir-2,578,562 12/1951 Lapadura... 240/4629 X mingh m, Engl n 3,316,4424/1967 Zuse ..315/83 1 Notice: The portion of the term of this patentsub f sequent to Dec 23, 1986, has been ones l c almed PrimaryExaminer-James W. Lawrence [22] Filed: Feb. 12, 1969 AssistantExaminer--D. C. Nelms pp No: 798,744 Attorney-Holman & Stern Related US.Application Data EXEMPLARY CLAIM [63] Continuatiomimpan of 734300 June 4l. Alighting system fora road vehicle, comprising in combina- 1968 whichis a continuationdmpan of Ser. tion alight source and associated lensfor producing a beam of 485,788, Sept. 8 1965 abandne light lllummatlngthe road in front of the vehicle, a mask having therein an aperture,focusing means associated with the [30 1 Foreign Application priorityData light source and arranged so that an image of the light sourceappears in the aperture, and a well defined image of the aper- OCI. i,1968 Great Blltalfl ..46,450/68 tu e i roje ted forwardly to constitutesaid beam a shutter movable from a rest position across the aperture,and means U.S-

se sitive to received from an oncoming vehicle for 250/205 315/82,315/83 progressively moving the shutter across the aperture so as to [5Int. CI. ut off uffi ient of the beam to avoid the driver of [58] Fieldof Search ..250/217, 205, 229; 315/82, the oncoming vehic|e 6 Claims, 19Drawing Figures PATENTEDJUH271972 3,673,421

sum 01 0F 10 P'A'TENTEUJum 1972 sum 02 or 10 FIG].

PATENTEDJUHZY I972 sum 03 HF 10 PATENTEDJum 1972 SHEET 0 b 0F 10 FIG.75.

PATENTEDJum m2 sum as or 10 PATENTEDJUN27 1972 saw 07 or 10PATENTEDJUINIQYZ v 3.673.421

sum user 10 PAIENTEDJum 1272 saw 10 or 10 LIGHTING SYSTEMS FOR ROADVEHICLES This application relates to lighting systems for road vehicles,and is a continuation-in-part of our US. Application Ser. No. 734,300filed 4th June 1968 which, in turn, is a continuationin-part applicationof our US. Application Ser. No. 485,788, filed 8th Sept. 1965, nowabandoned.

According to one aspect of the invention, a lighting system comprises incombination a light source and associated lens for producing a beam oflight illuminating the road in front of the vehicle, a mask havingtherein an aperture, focusing means associated with the light source andarranged so that an image of the light source appears in the aperture,and a well defined image of the aperture is projected forwardly toconstitute said beam, a shutter movable from a rest position across theaperture, and means sensitive to light received from an oncoming vehiclefor progressively moving the shutter across the aperture so as to cutoff sufficient of the beam to avoid dazzling the driver of the oncomingvehicle.

IN THE ACCOMPANYING DRAWINGS,

FIGS. 1 and 2 are diagrammatic plan views of a projector and a receiverrespectively of a lighting system according to one example of theinvention,

FIGS. 3 to 5 are respectively, side, front and plan views of projectorand receiver shown in FIG. 1 together with part of a milliameter withwhich they are associated,

FIGS. 6 and 7 respectively are views similar to FIGS. 1 and 2 of amodified projector and receiver,

FIG. 8 is a diagrammatic representation of the modified lighting systemutilizing the projector and receiver shown in FIGS. 6 and 7.

FIG. 9 is a block diagram illustrating a modification of the systemillustrated in FIG. 8,

FIG. 10 is a perspective view of the modified system illustrated in FIG.9.

FIG. 11 is a view similar to FIG. 10 of a further modification,

FIGS. 12 and 13 are side elevational and part sectional plan viewsrespectively of the projector shown in FIG. 1 1,

FIG. 14 is a view similar to FIG. 11 showing a modified dampingarrangement,

FIG. 15 is a view similar to FIGS. 6 and 7 showing a modified lensarrangement,

FIGS. 16 and 17 are sectional views of alternative forms of lensarrangement,

FIG. 18 is a front view of the lens arrangement shown in FIG. 16 and,

FIG. 19 is a view similar to FIG. '11 showing a further modification.

Referring first to FIGS. 1 to 5 of the drawings, a road vehicleincorporates a light projector shown in FIG. I and a light receivershown in FIG. 2. The projector includes a bulb 11 having an elongatedfilament 12 the center of which is situated at one focus of apart-ellipsoidal mirror 13. Parallel to the filament is a plate 14having therein a rectangular aperture 15 the center of which lies at theother focus of the mirror 13, so that an image of the filament appearsin the aperture 15.

Light passing through the aperture 15 strikes a plane mirror 16 silveredon its front surface andpositioned at 45 to the plate 14, and thencepasses through a plano-convex lens 17 which provides a beam of lightprojecting forwardly of the vehicle. The optical distance between theaperture 15 and lens 17 is equal to the focal length of the lens 17, sothat a well defined image of the aperture is projected forwardly, as abeam of rectangular cross section.

Movable across the aperture is a shutter 18 which prevents parts of thelight from the filament from reaching the mirror. The arrangement issuch that progressive movement of the shutter masks an increasingportion of the beam starting from the side of the beam nearer the centerof the road.

The receiver includes a piano-convex lens 19 which in use directs aparallel beam of light received from an oncoming vehicle onto a mirror21 silvered on its front surface positioned at 45 to the oncoming beam.The mirror 21 directs the light through an aperture 22 in a second plate23, the optical distance between the lens 19 and aperture 22 being equalto the focal length of the lens 19. Light passes through the aperture 22and thence through a converging lens 24 onto a photocell 25. Thearrangement is such that an image of the lens in the receiver falls onand almost fully covers the sensitized surface of the cell 25. In thisway, the circular image of the receiver lens falls centrally on thephotocell irrespective of the position of the image in the aperture 22.If the image falls outside the aperture 22, no light falls on the cell,and so the receiver is to this extent sensitive to the direction of theincoming light.

In use assuming that the projector and receiver are operative, lightfrom an oncoming vehicle falling on the photocell 25 produces a currentwhich is fed into an amplifier which energizes an instrument (which isherein referred to as a milliammeter) having the construction of astandard milliammeter without the usual scale. The pointer of themilliammeter, which assumes a position corresponding to the currentflowing in the milliammeter, is in the form of a diametrically extendingarm 26 having the shutter 18 at one end thereof, and a second shutter 27movable across the aperture 22 positioned at the other end thereof. Theshutter 27 moves across the aperture 22 until the image of lights froman oncoming vehicle is covered, at which point the photocell 25 ceasesto produce current and the shutter 27 moves back again. The amplifier isdesigned to damp fluctuations in the milliammeter, which may itself bedamped, and so the shutter 27 assumes an equilibrium position with theleading edge of the shutter 27 at a position corresponding to theposition of the image in the aperture 22. At the same time the shutter18 moves across the aperture 15 to reduce the width of the projectedbeam. The optical axes of the projector and receiver are so arrangedthat the projected beam is always spaced from the driver of the oncomingvehicle so that he is not dazzled. Moreover, the aperture 22 in thereceiver is slightly longer and wider than the aperture 15 in theprojector so that irrespective of the angle of approach of the oncomingvehicle the shutters 18, 27 will move sufficiently to avoid dazzle. Thusin the specific case when the image of the lights of an oncoming vehicleis at the extreme end of the aperture 22 the shutter 18 can remain fullyclosed, because light still falls on the photocell 25 to hold theshutters 18, 27 in position. The system described is intended to be usedat the same time as the normal dipped beams of a road vehicle and afilter 20 is used to remove the red and infra-red wave-lengths from theprojected beam. The photocell 25 is sensitive only to the removedwave-lengths, and so the milliammeter will be operated as explainedabove by an approaching vehicle, but the risk of unwanted operation ofthe milliammeter, for example by light emanating from the projector andreflected from a wall, is reduced.

If desired, the lens 17 may be replaced by two thin lenses or by anaspherical lens to enable the intensity of the projected beam to beincreased by use of a larger aperture. Moreover the two thin lenses orthe aspherical lens can, if desired, be achromatic.

Referring now to FIGS. 6, 7 and8, in a modification the mirror 16, 21are dispensed with so that the optical paths of the projector andreceiver are straight and parallel and the arm 26 is replaced by apulley wheel 28. The shutter l8 is carried by a rod 29 which issupported for substantially axial movement by a pair of leaf springs 31.The rod 29 also carries a second shutter 27 associated with the aperture22in the receiver. A strap 32 is secured at one end to an extension ofone of the springs 31 and extends round the wheel 28, the arrangementbeing such that as the current is fed to the milliammeter in respect tolight falling on the photocell 25, the shutters 18, 27 will be movedacross their respective apertures 15, 22, in a similar manner to thatdescribed above, movements of the rod 29 being damped by an eddy currentbrake33.

1n the further modification shown in FIGS. 9 and 10 the shutters 18, 27are operated by a vacuum unit in place of the milliammeter. The vacuumunit includes a diaphragm one side of which is subjected to atmosphericpressure while the other side is subjected to a reduced pressurecontrolled by an electro-magnetic bleed valve, which in turn iscontrolled by the photocell 25. Movement of the diaphragm in response tochanges in the reduced pressure are transmitted to the shutters 18, 27to open and close the apertures 15, 22. A convenient source of reducedpressure is the engine inlet manifold.

it will be appreciated that since a vacuum unit is more powerful thanthe milliammeter movement it is not necessary to use the delicate leafspring arrangement to support the rod 29 when a vacuum unit is used.

FIG. 10 illustrates a more robust arrangement utilizing a vacuum unit.The vacuum unit 35 is carried by a bracket 37 at one end of a back plate36 which has formed therein the apertures 15, 22, the plate 36constituting the masks 14, 23. Pivotally mounted on the plate 36 formovement in a plane parallel to the plate 36 are a pair of parallel arms38 39 and pivotally mounted at the lower ends of the arms 38, 39 is therod 29 carrying the shutters 18, 27. Extending from the vacuum unit 35,through the bracket 37 and a further bracket 41 is a link member 42which is engaged at its end remote from the unit 35 with the arm 38 at apoint on the arm 38 adjacent the pivotal connection of the arm 38 withthe plate 36. interposed between the arm 38 and the bracket 41 andsurrounding the member 42 is a compression spring 43 which urges thearm38, and consequently the arm 39 and the rod 29, to a position where theapertures 15, 22 are open. The vacuum unit 35 is controlled in themanner previously described to operate the shutters 18, 27.

In a still further modification shown in FIG. 11 the milliammeter isreplaced by an instrument 44. The instrument 44 comprises a rectangularsoft iron frame 45, the limbs of which are of rectangular cross section.The frame 45 is secured to a plate 36, which constitutes the masks 14,23, so as to extend in a plane at right angles thereto, the long limb45a of the frame 45 adjacent the plate 36 being spaced from the plate36-and being arranged parallel to and below the apertures 15, 22. Aferrite magnet 46 is secured to-the other long limb 45b of the frame andis housed between the limbs 45a, 45b of the frame, the width of themagnet 46 being substantially equal to the length of the limb 45b of theframe. The north pole of the magnet 46 is in contact with the limb 45b,and since the frame 45 is a closed circuit the whole of the frame 45isof north polarity with respect to the south pole of the magnet 46, thesouth pole of the magnet 46 being spaced from the limb 45a of the frame45 by an air gap. Thus part of the magnetic field of the frame 45 andthe magnet 46 extends between the limb 45a.of the frame 45 and the southpole of the magnet 46 at right angles to the limb 45a.

Slidably mounted on the limb 45a of the frame 45 is a spool 47 having arectangular annular cross section, on which is wound a winding 48 thewinding 48 surrounding the limb 45a of the frame 45. The spool 47carries an aluminum strip 49, the ends of which define respectively theshutters 18, 27. The shutters 18, 27 are so positioned that as the spool47 moves along the limb 45a of the frame 45, the shutters 18, 27 will bemoved across the apertures 15, 22, respectively. The spool 47 is urgedto a position wherein the apertures 18, 22 are uncovered by a wirespring 51, one end of the spring 51 being adjustably secured to theplate 36 while the other end of the spring 51 engages the shutter 18.

In order that electrical connections can be made to the winding 48without hindering the movement of the spool 47, there are provided apair of fine copper wire pigtails 52, which are electrically connectedat one end to the ends of the winding 48 respectively.

The other ends of the pigtails 52 are connected respectively to the endsof a pair of leads 53 which in turn are connected to the amplifier whichreceives current from the photocell 25.

In order to minimize the risk of breakage of the pigtails $2 owing tomovement of the leads 53 in use, the limb 45b of the frame 45 is formedwith two parallel pairs of parallel bores, each leads 53 being threadedthrough a respective pair of bores prior to the connection thereto ofthe pigtails 52. Thus as light falls on the photocell electric currentflows in the winding 48, and the spool 47 and the shutters 18, 27 aremoved, against the action of the spring 51, so that the shutters 18, 27move across the apertures 15,22. The outer shutter 27 is moved acrossthe apertures 22 until the image of the lights of the oncoming vehicleis covered, at which point the photocell causes to produce current andthe spool 47 moves back again under the action of the spring 51,whereupon the photocell again produces a current. Thus the spool 47 andconsequently the shutters 18, 27 tend to reciprocate through a veryshort stroke about the point'at which the image of the lights of theoncoming vehicle are covered.

In order to stabilize the spool 47 to reduce the reciprocation, thestrip 49 has slidably mounted thereon, a block ofpolytetrafluoroethylene (not shown) which is engaged between a pair oflugs upstanding from the plate 36. The lugs are spaced apart by adistance fractionally larger than the length of the p.t.f.e. block. Thuswhen the spool 47 is moved from its rest position the block is movedinto engagement with one of said lugs whereupon movement of the block isarrested. The spool 47 continues to move and the strip 49 slidesrelative to the block, it being appreciated that the coefficient ofdynamic friction of p.t.f.e. is very low. However, when the spool 47reaches the position whereinthe shutter 27 covers the image of thelights from the oncoming vehicle the reciprocation of the spool aredamped by the added inertia of the p.t.f.e. block since the block wouldbe carried back and forth between said lugs. Moreover should the inertiaof the block be insufficient to damp the reciprocation of the spool theneach time the block contacts one of the lugs, movement of the strip 49relative to the block will be resisted by the static friction of theblock and the strip 49 it being appreciated that the coefficient ofstatic friction of any material is greater than the coefficient ofdynamic friction of that material.

The p.t.f.e. block can be engaged with the strip 49 between the shutters18, 27 or can be engaged with an integral extension at one end of thestrip 49 and moreover said lugs can be defined by the walls of anaperture in the plate 36 in which the block is positioned.

Thus when light from an oncoming vehicle enters the receiver the spool47 assumes an equilibrium position with the leading edge of the shutter27 at a position corresponding to the position of the image in theaperture 22. At the same time the shutter 18 has been moved across theaperture 15 and so reduces the width of the projected beam. The opticalaxes of the projector and receiver are parallel and are so arranged thatthe projected beam is always spaced from the driver of the oncomingvehicle so that he is not dazzled. The leading edge of shutter 18 is inadvance of the leading edge of the shutter 27 thereby ensuring that theoncoming drivers eyes are always in shadow, and moreover the aperture 22is slightly wider and longer than the aperture 15. Thus, in the specificcase when the image of the lights of an oncoming vehicle is at theextreme end of the aperture 22 the shutter 18 can remain fully closed,because light still falls on the photocell 25 to hold the shutters 18,27 in position. The system described is intended to be used at the sametime as the normal dipped headlamp beams of a road vehicle, and again afilter 20 is used to remove the red and infra-red wave-lengths from theprojected beam, the photocell 25 being sensitive principally to the redand infra-red wavelengths.

Referring now to FIGS. 12 and 13 the bulb ll of the projector includes asealed, two part envelope having a part ellipsoidal rear portion 54a andintegral therewith, a hemispherical front portion 54b the center ofcurvature of portion 54b and one focal point of the portion 54a being acommon point. The inner surface of the envelope is coated so as toconstitute the mirror 13, a circular area at the center of thehemispherical portion 5412 being left clear to constitute a window 55.The filament 12 of the bulb is positioned within the envelope so as toextend transversely through a point constituting the center of theportion 54b and said one focal point of the portion 54a and the envelopefurther includes upper and lower axially aligned cylindrical portions56, 57 the axis of which passes through said point, at right angles tothe axis of the filament 12. A pair of connecting leads 59 extendthrough the wall of the portion 57 of the envelope and are connectedrespectively to the ends of the filament 12. The reflective portion ofthe envelope of the bulb 11 is such that a magnified image of thefilament 12 is produced at the other focal point of the portion 54a ofthe envelope. As previously stated the image of the filament 12 isprojected into the aperture and in order to position the bulb 11 so thatthe other focal point of the portion 54a of the envelope lies in theplane of the aperture 15, the portion 54b of the envelope is engagedwith the free end of a hollow cylindrical member 61 which is secured tothe plate 36. The member 61 surrounds the aperture 15 and extends atright angles to the plate 36, the axis of the member 61 passing throughthe mid-point of the aperture 15. Moreover, the length of the member 61is such that when the bulb 1 1 is engaged therewith then the image ofthe filament 12 projected by the bulb 11 will fill the aperture 15.

The engagement of the portion 54b of the envelope with the end of themember 61 constitutes a ball and socket joint between the bulb 11 andthe member 61, the bulb 11 being pivotable with respect to the member 61about the common point defining said one focus of the portion 540 andthe center of curvature of the portion 54b. In order to maintain thebulb 11 in engagement with the member 61, there is provided a collar 62which is supported in a rigid bracket 63 secured to the plate 36 of theprojector, the portion 57 of the envelope of the bulb 11 being receivedas a push fit in the collar 62. In addition to the collar 62 there isprovided a second collar 64 which is carried at one end of a bracket 65which is also secured to the plate 36. The bracket 65 is hinged and ismovable to a position wherein the portion 56 of the envelope of the bulbis received as a push fit in the collar 64.

The collars 62, 64 and their respective rackets 63, 65 are sodimensioned that when the collars 62, 64 are engaged with the portion54b of the envelope of the bulb 11 is engaged with the member 41 thenthe magnified image of the filament 12 of the bulb will be projectedinto the aperture 15.

In order to replace a bulb 11 which has failed the collar 64 isdisengaged from the portion 56 by hinging the bracket 65 to the positionshown in dotted lines in FIG. 12. The faulty bulb is then removed andreplaced by a new bulb, the connections to the new bulb are made by theleads 59 and the collar 64 is then engaged with the new bulb.

In a modification of the system described with reference to FIGS. 11 to13, the polytetrafluoroethylene damping block is dispensed with, and theend of the wire spring 51 is connected to the spool 47 by means of aflexible thread 51a.

In order to stabilize the spool 47 to reduce the reciprocation thereofthe wire spring 51 is enclosed in a moulded synthetic resin sheath 51b(FIG. 14). The sheath 51b is moulded, in for example, p.v.c. and has aflaccid nature, that is to say that the sheath has no inherentresilience. The sheath 51b serves to damp vibrations of the wire spring51, and so consequently damps the reciprocation of the spool 47 and theshutters 18, 27. In a modification of the system a second wire spring,with associated sheath, acts between the plate 36 and an extension ofthe shutter 27, so that the two springs act in unison on the shutterassembly.

Each sheath can be moulded around its respective wire spring, or can bethreaded on to its respective wire spring and held in place by anyconventional means.

The filter which, as described above, is included in the projector toremove the red and infra-red wave-lengths from the projected beam isdispensed with in a modification. In the modification the mirror 13 is adichroic mirror the coating of which is such that it reflects allwave-lengths in the light from the filament 12 other than red andinfra-red, but transmits the red and infra-red wave-lengths. Thus thered and infra-red wave-lengths are not present in the projected beam andsince the photocell 25 is principally sensitive to these wave-lengthsthe risk of operation of the system by its own reflected light isminimized.

Referring to FIG. 15, it will be appreciated that since the projectorand receiver must be accurately correlated with one another to ensurethat the driver of an oncoming vehicle is not dazzled, then it isimportant that the lenses 17, 19 are positioned accurately with respectto one another on the casin g of the system. Thus in a modification ofthe lens arrangement in order to minimize the risk of misalignment ofthe lenses 17, 19 with respect to one another, the lenses 17, 18 aremoulded as integral parts of a rectangular plate 66. Thus the lenses l7,19 are always maintained in said accurately predetermined relation toone another, and since the lenses are integral with one another, thetolerances involved in the mounting of the lenses are kept to a minimum.

FIGS. 16, and 18 show a practical form of lens assembly wherein thereceiver lens 19 is crescent shaped and the projector lens 17 is acompound lens. To ensure accuracy in mounting the lenses 17, 19 relativeto one another one element 17a of the lens 17 is moulded integrally withthe lens 19, the element 17a and the lens 19 being part of a plate 137.The second element 17b of the lens 17 is moulded separately but isaccurately positioned relative to the element 170 by locating means onthe plate 137, the element 17b being secured to the plate 137 by anadhesive. There is further provided a masking plate 138 which masks theareas of the plate 137 other than the lens 19 and the element 17a. Thefront surfaces of the plate 137, the element 17b, and the plate 138 areprotected by a transparent cover 139 and the assembly so formed issecured together by an annular rubber frame 141 which seals theperiphery of the assembly. The assembly is secured in position on thecasing 110 of the system by a clamping ring 142 secured to the casing 110 by screws.

The lens assembly shown in FIG. 17 differs from that shown in FIG. 16 inthat the lens 19 and the lens element 17a are not integral parts of aplate. In the alternative lens assembly shown in FIG. 17 there isprovided a moulded rectangular lens support member 144 having therein acrescent shaped aperture 145 and a generally circular aperture 146. Thewalls of the aperture 145 are shaped to receive and locate the crescentshaped receiver lens 19 which can be secured to the member 44 using anadhesive. The projector lens 17 is again in two elements 17a 17b and thewalls of the aperture 146 are shaped to receive and locate the elements17a, 17b which can also be secured to the member 144 using an adhesive.A masking plate 147 having therein a crescent shaped aperture and agenerally circular aperture is engaged with the front face of theassembly and masks the assembly other than the lenses 17, 19. Themasking plate 147 and a transparent cover 148 are secured in position byan annular rubber frame 149 which seals the periphery of the assemblyand the assembly is secured in position on the casing of the system by aclamping ring 151 secured to the casing 110 by screws. Since the lenses17, 19 are located by a common member then the tolerances involved inthe mounting of the lenses are reduced as compared with providing thelenses with separate mounting members.

The radius of the crescent shaped portion of the receiver lens 19 issubstantially equal to the radius of the projector lens 17 and the lens19 is so positioned with respect to the projector lens 17 that theconcave edge of the lens 19 is parallel with the convex edge of the lens17, thereby reducing the overall width of the lens assembly as comparedwith an assembly wherein both of the lenses are generally circular.

The projector lenses 17 in the examples described above are notachromatic and so a certain amount of dispersion of the projected beamoccurs. The blue component of the projected beam will occur on thefringes of the beam after dispersion and since the blue lights are usedby certain traffic authorities to denote traffic hazards then it isdesirable that oncoming motorists do not see blue light emanating fromthe projector of the system. The emission of blue light from the systemcan be minimized by making the lens 17 achromatic. Altematively, theblue light can be removed by choosing the dichroic coating of the mirror13 so that the mirror 13 reflects neither the blue wave-lengths nor thered and infra-red wave-lengths. Furthermore the blue light can beremoved by coating the lens 17 or a corresponding area of thetransparent cover of the lens assembly with a material which is opaqueto blue light so that the blue light in the projected beam is nottransmitted.

The modified system shown in FIG. 19 is suitable for use both incountries having left-hand rule of the road and countries havingright-hand rule of the road. The modified system is similar to thesystem described with reference to FIG. 11 and parts common to bothsystems carry the same reference numerals. In the system shown in FIG.19 the spool 47 carries an aluminum strip 231 on which are integrally orseparately mounted three shutters 241, 242, 243, the spool 47 is urgedto the central position shown in which the shutters are spaced from bothapertures 15, 22 by one of a pair of leaf springs 244, 245 mounted onthe plate 36. The spool is coupled to the leaf springs by aself-supporting filament 246 the central portion of which is connectedto the spool and the ends of which extend through holes in the ends ofthe leaf springs 244, 245, the ends of the filament 246 having connectedthereto studs 247. Electrical connections are made to the winding 48through fine copper wire pigtails 52, which are electrically connectedat one end to the ends of the winding 48 and are further connected tothe ends of a pair of leads 53 coupled to the amplifi- The vehicle isprovided with a selector switch which determines whether the lightingsystem is suitable for use in a country having a left-hand rule of theroad or a right-hand rule of the road. The selector switch is simply areversing switch controlling the direction of current flow to thereceiver, and for the moment it will be assumed that the switch is setfor a country with a left-hand rule of the road.

Normally, the shutters are in the position shown and a beam of light isprojected through the aperture 15 as previously explained. When lightfrom an oncoming vehicle enters the aperture 22 it falls on thephotocell 25 so that current is fed to the winding 48, this currentcausing the spool 47 to move to the left, so that the shutters 243 and242 move across the apertures l and 22 respectively. The filament 246slides through the leaf spring 244, which therefore is not stressed, andwhen the stud 247 reaches the side of the casing supporting the plate 36the filament bends with the stud 247 sliding down or up the wall of thecasing. The leaf spring 245 is, of course, stressed by the movement ofthe spool 47.

Assuming for the moment that the two approaching vehicles arestationary, then the system assumes an equilibrium position with theleading edge of the shutter 242 at a position corresponding to theposition of the image in the aperture 22. At the same time, the shutter243 assumes a position in the aperture in which the width of theprojected beam is such that the driver of the oncoming vehicle is notdazzled. The leading edge of the shutter 243 is arranged to be just inadvance of the leading edge of the shutter 242, so ensuring that theoncoming drivers eyes are always in shadow, and furthermore the aperture22 is slightly wider and longer than the aperture 15 so that if theimage of the lights of an oncoming vehicle is at the extreme end of theaperture 22, the shutter 243 can remain fully closed, because lightstill falls on the photocell 25 to hold the shutters 242, 243 inposition. It will of course be appreciated that the system described isintended to be used at the same time as the normal dipped headlamp beamsof a road vehicle. In practice of course the vehicles will beapproaching each other continuously so that the position of the image inthe aperture 22 changes continuously, but the system automati callyadjusts the position of the shutters so that the oncoming driver is notdazzled at any time. The spring 245 urges the shutters back to theposition shown at all times, so that when no further input is receivedfrom the amplifier the parts assume the position shown.

It will be apparent that when a left-hand rule of the road is beingobserved, the shutter 241 plays no part at all in the operation. Whenthe selector switch is set for right-hand rule of the road, theoperation is similar to that described above, except that the shutter242 is now used to control the projected beam, with the shutter 241controlling the received beam and the shutter 243 playing no part in theoperation. In these circumstances of course the spring 245 is unstressedbut the spring 244 is stressed.

It will be appreciated that by having a self-supporting filament 246which, depending on the direction of movement of the spool, slidesrelative to one of the leaf springs 244, 245, the overall width of theplate 36 can be reduced, because if the filament 246 were connected toboth leaf springs, then when for example, the spring 244 was in use, thespring 245 would also flex and move to the right, so that it would benecessary to allow for this movement in the width of the plate 36. Thefilament 246 is small in diameter, and although it passes through a holein the spool 47 and is secured thereto, it does not substantially affectthe magnetic properties of the spool.

In a modification of the system, the ends of the filament 246 are bentupwardly and secured to the springs 244, 245 so that the filament cannotslide relative to the springs. The dimensions are such that the distancefrom the frame 45 to the springs in the rest position is less than thedistance from the frame 45 to the spool so that when the spool moves tothe right, for example, the part of the filament between the frame 45and the spring 245 loops downwardly. The operation is similar when thecarriage moves to the left.

In any of the examples described above the light source of the projectorcan be a bulb, the envelope of which constitutes a reflector, asdescribed above or can be a bulb with a clear envelope having a separatereflector associated therewith. Moreover, the leads 53 and pigtails 52can be replaced by flexible leads electrically connected to the windingand secured to the limb 45b of the frame 45 by means of a clamping platewhich is held in position by screws.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent is;

l. A lighting system for a road vehicle, comprising in combination alight source and associated lens for producing a beam of lightilluminating the road in front of the vehicle, a mask having therein anaperture, focusing means associated with the light source and arrangedso that an image of the light source appears in the aperture, and a welldefined image of the aperture is projected forwardly to constitute saidbeam, a shutter movable from a rest position across the aperture, andmeans sensitive to light received from an oncoming vehicle forprogressively moving the shutter across the aperture so as to cut offsufficient of the beam to avoid dazzling the driver of the oncomingvehicle.

2. A lighting system as claimed in claim 1 including a winding securedto said shutter, means for producing a magnetic field passing throughsaid winding so that said winding and consequently the shutter arecaused to move linearly in a direction to move the shutter across theaperture, when the winding is energized, resilient means urging theshutter in a direction to uncover the aperture, said means sensitive tolight received from an oncoming vehicle serving to energize said windingso that said shutter is moved progressively across the aperture to cutoff sufficient of said beam of light to avoid dazzling the driver of theoncoming vehicle.

3. A system as claimed in claim 1, in which said means sensitive tolight from an incoming vehicle includes a light receiver comprising alens for projecting an image of light from an oncoming vehicle into asecond aperture in a second mask, and thence onto a photocell whichenergizes a means for moving said first shutter, said means also movinga second shutter across the second aperture, said first and secondshutters being moved by equal mounts simultaneously, said first andsecond shutters and associated apertures thereby defining ters arecarried by and movable by a rod which extends substantially parallelwith the plane of the mask, the rod being operated under the control ofsaid means.

6. A system as claimed in claim 3, wherein the elements thereof aredisposed on a common mounting.

1. A lighting system for a road vehicle, comprising in combination alight source and associated lens for producing a beam of lightilluminating the road in front of the vehicle, a mask having therein anaperture, focusing means associated with the light source and arrangedso that an image of the light source appears in the aperture, and a welldefined image of the aperture is projected forwardly to constitute saidbeam, a shutter movable from a rest position across the aperture, andmeans sensitive to light received from an oncoming vehicle forprogressively moving the shutter across the aperture so as to cut offsufficient of the beam to avoid dazzling the driver of the oncomingvehicle.
 2. A lighting system as claimed in claim 1 including a windingsecured to said shutter, means for producing a magnetic field passingthrough said winding so that said winding and consequently the shutterare caused to move linearly in a direction to move the shutter acrossthe aperture, when the winding is energized, resilient means urging theshutter in a direction to uncover the aperture, said means sensitive tolight received from an oncoming vehicle serving to energize said windingso that said shutter is moved progressively across the aperture to cutoff sufficient of said beam of light to avoid dazzling the driver of theoncoming vehicle.
 3. A system as claimed in claim 1, in which said meanssensitive to light from an incoming vehicle includes a light receivercomprising a lens for projecting an image of light from an oncomingvehicle into a second aperture in a second mask, and thence onto aphotocell which energizes a means for moving said first shutter, saidmeans also moving a second shutter across the second aperture, saidfirst and second shutters being moved by equal mounts simultaneously,said first and second shutters and associated apertures thereby definingmeans correlating the field of illumination of the beam of projectedlight with the field of view of the light receiver.
 4. A system asclaimed in claim 3 in which the shutters and apertures are sodimensioned reLative to one another that even when the first aperture iscompletely covered, light falls on the photocell.
 5. A lighting systemas claimed in claim 3 in which said shutters are carried by and movableby a rod which extends substantially parallel with the plane of themask, the rod being operated under the control of said means.
 6. Asystem as claimed in claim 3, wherein the elements thereof are disposedon a common mounting.